A Compact 2-D Phased Array Fed by 4x4 Butler Matrix Without Crossover in Broadside Coupled Stripline For Sub-6GHz 5G Applications

A compact 2-D phased array based on a compact 4x4Butler Matrix without crossover designed in Broadside Coupled Stripline (BCS) technology is proposed for Sub-6GHz 5G applications. The proposed 4x4 Butler Matrix (BM) is composed only of four 3dB/90 degrees broadside couplers and two 45 degrees phase shifters. The phase responses of (+/- 90 degrees) and (+/- 45 degrees, +/- 135 degrees) obtained respectively in x- and y-directions allow the 4x4BM to feed a 2x2 array antenna. The implementation of the 4x4 BM in BCS without crossover highly improves the compactness and the amplitude distribution. Moreover, the proposed 4x4BM can be easily integrated under the 2x2 patch array antennas by probe via to produce four beams in both elevation and azimuth directions. The physical areas of the proposed 4x4BM and 2x2 array module are only 0.25 lambda(0)x0.3 lambda(0)x0.04 lambda(0) and 0.8 lambda(0)x0.8 lambda(0)x0.04 lambda(0) respectively. To validate the concept, a prototype operating in the frequency range of 3-7GHz is fabricated and measured. The measurement results agree well with the simulations.